<template>
  <!--隐式类型转换-->
  <div class="todo-footer" v-show="total">
    <label>
      <input type="checkbox" v-model="isAll" />
    </label>
    <span>
      <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>


<script>
export default {
  name: "MyFooter",
  props: ['todos'],
  computed: {
    total () {
      return this.todos.length;
    },
    doneTotal () {
      return this.todos.reduce((todoTotal, todo) => {
        return todoTotal + todo.done;
      }, 0);
    },
    isAll: {
      get () {
        return this.total === this.doneTotal && this.doneTotal > 0;
      },
      set (value) {
        //采用自定义事件来修改
        this.$emit('checkAllTodo', value);
      }
    }
  },
  methods: {
    clearAll () {
      //修改为自定义事件
      this.$emit('clearAllDoneTodo');
    }
  }
}
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>
